Antibacterial metabolites from Paecilomyces niveus and their chemophenetic significance

Optimization of cultural conditions for biomass and antibacterial metabolite production by Aspergillus fumigatus strain MF1

A chemical genetic approach using genetically encoded reporters to detect and assess the toxicity of plant secondary metabolites against bacterial pathogens

Antibacterial and antiviral metabolites from cyanobacteria: Their application and their impact on human health

To combat the increasing numbers of antibiotic resistant strains of pathogenic bacteria new source of antibacterial agents are desperately needed. This study was aimed to discover new marine bacteria having antibacterial activity from marine soil samples of Sundarbans, Bangladesh. Using starch-casein-nitrate-agar medium thirty nine marine bacteria colonies were isolated as pure isolates from nine marine soil samples. Each of the isolates was preserved in both short term and long term basis. Based on the aerial and substrate mycelia color of the isolates they were grouped into five color series and were screened for their antibacterial activity against a series of test bacteria. Among thirty nine pure isolates twenty four isolates (61.5%) exhibited moderate to high activity against three grampositive and four gram-negative bacteria. This is due to the antibacterial metabolites secreted in the medium by most of the isolates. It suggested that Sundarbans may be an interesting, valuable and potential source for the exploration of novel marine bacteria with the potential to yield useful new antibacterial secondary metabolites of pharmaceutical interest.Bangladesh Pharmaceutical Journal 18(1): 53-60, 2015

Formulation of nanoencapsulation of antibacterial metabolites from the fermentation of actinomycete strain designed as TP5 has been carried out. Nanoencapsulated formulations performed with Na alginate polysaccharides obtained from brown seaweed can maintain the antibacterial metabolite activity. This study aims to enhance antibacterial activity in nanoencapsulated formulations of antibacterial metabolites with ionic gelation technique using Na alginate and CaCl2. The nanocapsules were prepared by combining the extracellular secondary metabolite Nocardia sp. TP5 with the encapsulation sourced from Na alginate and CaCl2 by ionic gelation technique. The manufacturing methods include fermentation of Nocardia sp. TP5, nanoencapsulated formulation by varying the concentration and ratio of Na alginate, CaCl2, antibacterial metabolites, as well as analysis of nanocapsules. The analysis and characterization of nanoencapsulation using SEM-EDS and PSA included: surface morphology, particle size, chemical constituents, and zeta potential, as well as antibacterial testing against Escherichia coli and Staphylococcus aureus. The results showed that the best-nanoencapsulated formula contains the composition of Na alginate 0.3%, CaCl2 0.06% with a ratio of Na alginate: CaCl2: antibacterial metabolite is 2: 4: 1. The capsule particles formed are evenly distributed over the entire surface with a particle size of 425 nm, zeta potential of -27 mV, and antibacterial activity inhibited the growth of E. coli and S. aureus by 20 and 21 mm, respectively. The variation of the appropriate concentration ratio of Na alginate and CaCl2 greatly affects the uniform nanocapsules size and increases the antibacterial activity.

Objectives: This paper aimed to optimize some essential nutritional components (carbon, nitrogen, and phosphate) of fermentation medium necessary for the production of antibacterial metabolites from Streptomyces sp.Materials and Methods: Streptomyces sp. LH9 previously isolated from desert soil in Karbala Province, Iraq. This strain produced antibiotic against 4 pathogenic bacteria, including Escherichia coli, Staphylococcus aureus, Streptococcus agalagtiae, and Pseudomonas aeruginosa. For optimizing, the essential nutritional requirements such as carbon, nitrogen, and phosphate in fermentation media different concentrations of these sources were used to improve the antibacterial metabolite production.Results: All the studied nutritional parameters were had impacts on the antibacterial metabolite production from Streptomyces sp. LH9. The actinobacterial strain produced a highest antibiotic metabolites when was grown in the fermentation medium supplemented with 2% dextrose (as a sole carbon source), 0.05% peptone (as a sole nitrogen source), and 0.05% K2HPO4 at pH 7 and incubated under optimal conditions; at 30°C with 250 rpm (revolutions/min) agitation for 7 days.Conclusion: Streptomyces sp. LH9 was a good producer for antibacterial against Gram-positive and Gram-negative bacteria, which required simple nutritional supplements in the fermentation medium. Furthermore, could be utilized the industrial waste for improving the production in the most economic manner.

For the most part the probiotics development is aimed at finding new effective strains and / or formation of original microbial consortia. It is believed that for the implementation of a therapeutic effect, it is enough for strains to reach in the host's body. However, the experience in practical use of such drugs in most cases revealed their insufficient therapeutic activity. In the last decade, the number of reports on the effect of the microorganisms habitat conditions as a resolving factor on the manifestation of one or another functional activity by them has increased. Herewith, it was suggested about the key role of peptide (cytokine)-regulation in the implementation of this process. Many regulators of protein-peptide nature are hydrolysis products. This study was carried preliminary assessment of industrial hydrolysates as a source of regulatory substances that affect the growth and functional properties of the B. subtilis. The hydrolysates used effect on the B. subtilis growth was assessed by the bacterial growth curve. The hydrolysates effect on the B. subtilis functional activity was assessed by their ability to produce antibacterial metabolites. As a result of the study, the change nature in growth indicators testified that industrial hydrolysates, in addition to nitrogenous nutrients, contain a number of biologically active substances, with can both suppress and stimulate the B. subtilis growth. The dependence of the B. subtilis antibacterial metabolites formation on hydrolysates and their heat treatment is shown. The presence of both thermolabile and thermostable biologically active substances was noted. Keywords: Bacillus subtilis, biologically active substances, antibacterial metabolites, hydrolysates, probiotics.

Realizing an increasing need for a novel antibiotic, this study was carried out to screen antibacterial metabolites producing actinomycetes from 15 soil samples collected from Taplejung. Antibacterial metabolites producing actinomycetes were confirmed by primary screening and secondary screening. Macroscopic, microscopic, and biochemical characteristics were used for presumptive identification of probable actinomycetes genera. The potential isolate was cultured in starch casein broth for production of possible antibacterial compound. The antibacterial compound was extracted from fermented broth using organic solvents like ethyl acetate, n-butanol, chloroform, dichloromethane, and methanol. Among 24 isolates, only one (T18) showed antibacterial activity against both Gram-positive (Staphylococcus aureus and Bacillus subtilis) and Gram-negative (Escherichia coli, Salmonella Typhi and Pseudomonas aeruginosa) test-bacteria. The isolate was considered as Streptomyces spp based on microscopy and various biochemical, and physiological characteristics. Extracted antibacterial metabolite showed antibacterial activity with a MIC value of 1.2 mg/mL against E. coli (ATCC 25922). The chromatogram in Thin Layer Chromatography showed only one spot exhibited by extract with Rf value 0.87 suggested that the isolate produced a compound that was completely different from the spot with Rf value 0.94 produced by gentamicin (standard). This study revealed the distribution of the potent antibacterial metabolite producing actinomycetes in the soils of Taplejung.

Total 24 isolates with antimicrobial activity against Staphylococcus aureus, Escherichia coli, Bacillus cereus and Shigella castellani, out of 259 strains, were isolated from the internal of seven marine fishes. The extracellular metabolites of strain S14, isolated from the internal of shark, showed stronger inhibition against the four tested bacteria, including G-and G+ bacteria. Based on the 16S rDNA the sequencing analysis, the strain S14 belonged to a member of Staphylococcus epidermidis with 99% DNA similarity and named to Staphylococcus epidermidis S14. The Staphylococcus epidermidis S14 secreted rarely antibacterial substance in the stabilization period and the antibacterial active substances might be the secondary metabolites. The antibacterial metabolites were not hydrolyzed by pepsin, trypsin and lysozyme. The antibacterial metabolites were stable for 30 min to high temperature treatment at 100C and had higher antibacterial activity at neutral pH.

This study is the first to report on the statistical optimization of an antibacterial production medium for the marine bacterium Streptomyces aureofaciens A3. Glycolic and furoic acids have not been previously documented as metabolites produced by Streptomyces, especially by S. aureofaciens A3. The antibacterial metabolites were generated in an ISP4 medium enriched with artificial seawater with different concentrations of starch, NaCl, and ammonium sulfate. Media components were optimized through the Response Surface Method (RSM) using the Box-Behnken design (BBD) in submerged fermentation. Antibacterial metabolites produced during fermentation were extracted with ethyl acetate (EA) to obtain EA extracts. The extract activities were tested using the Kirby-Bauer method, and the extract compounds were annotated using GC/MS. The results showed that the specific concentrations of starch, ammonium sulfate, and NaCl enhanced the antibacterial activity for each tested bacteria were 11.06 - 12.07 g/L for starch and 1.39 - 1.56 g/L for ammonium sulfate and 1.76 - 2.45 g/L for NaCl. The media increased higher antibacterial activity against pathogens with rising percentages of inhibition zones of E. coli (62.33 %), S. aureus (9.41 %), S. typhimurium (48.69 %), P. aeruginosa (39.16 %) and B. subtilis (8.58 %), respectively. The inhibition zones of each test bacteria were 10.88 - 17.97 mm and categorized as strong antibacterial activity. GC/MS derivatization results showed that the annotated compounds in EA extracts consisted of primary metabolites such as glycolic acid, palmitic acid, stearic acid, lauric acid, myristic acid, oleic acid and secondary metabolites were furoic acid, phthalate acid, benzoic acid, methylmalonic acid. This study showed that the RSM method is efficient and effective for improving the activity of broad-spectrum antibacterial agents produced by S. aureofaciens A3. The application of RSM to optimize ISP4 medium enables the large-scale production of antibacterial metabolites for the pharmaceutical industry. HIGHLIGHTS The antibacterial activity of marine Streptomyces aureofaciens A3 was first optimized using the Response Surface Method with ISP4-modified media. Broad-spectrum antibacterial activity increases against all pathogenic bacteria with a media composition similar to seawater. The low ammonium sulfate concentration induces higher antibacterial activity against bacterial pathogens. GRAPHICAL ABSTRACT

Seventy-eight marine fungal strains were isolated from sediment samples collected off the coast of Nanji Island, Wenzhou, Zhejiang Province, China. Antibacterial screening using the agar disc method showed that 19 of the isolated strains could inhibit at least one pathogenic V ibrio from P seudosciaena crocea. Subsequent screening confirmed that nine strains produced antibacterial metabolites that had activity against one or several types of pathogenic V ibrio. Strain NJ0104 had the widest antimicrobial spectrum and strong activity, particularly against Vibrio parahaemolyticus-MM0810072. A preliminary study of NJ0104 antibacterial metabolites demonstrated that they had thermal stability up to 80°C, ultraviolet stability up to 40 min and pH stability between 4.0–7.0. In addition, the antibacterial metabolites were readily soluble in butanol. To identify the specific strain, the ITS-5.8S rDNA regions of NJ0104 were PCR amplified and sequenced. Based on the combination of phenotypic and genotypic data, the strain was identified as Arthrinium sp.

3,6,8-Trihydroxy-1-methylxanthone—an antibacterial metabolite from Penicillium patulum

In the science of drug discovery, ultraviolet (UV) irradiation has been applied to induce mutagenesis in fungi to provide possibilities for the stimulation or enhancement of fungal biosynthetic capabilities. This study was carried out to evaluate the effect of UV radiation on the biosynthesis of antibacterial secondary metabolites in an endophytic Lasiodiplodia theobromae. Using standard methods, the fungus was isolated from healthy leaves of Cola acuminata and identified based on PCR amplification and genomic sequencing of the internal transcribed spacer (ITS) region. Cultures of L. theobromae were exposed to UV radiation at different time intervals of 1, 2 and 5 min. The fungus was subjected to solid-state fermentation in rice medium before and after UV treatments. The fungal secondary metabolites were extracted and tested for antibacterial activity using the agar diffusion method. Compounds present in the obtained extracts were identified by HPLC and GC-MS analysis. At a concentration of 1 mg/ml, the extract of the wild type L. theobromae (untreated) was observed to only inhibit Staphylococcus aureus, with an IZD of 12 mm. However, the extract of UV-treated L. theobromae (2 min) inhibited S. aureus, Escherichia coli and Pseudomonas aeruginosa with an IZD of 10 and 4 mm respectively. A wide array of compounds in the phenolics, fatty acids, alkaloids and alkanes classes were identified in the UV-treated and untreated fungal extracts. Overall, UV treatments of L. theobromae stimulated the production of seventeen (17) new compounds that were not detected in the untreated strain. The study confirms UV irradiation as an effective method for stimulating microbial biosynthesis of new bioactive compounds, indicating a promising and potentially abundant source of new drug compounds from microorganisms.

Antibacterial secondary metabolite is a bioactive compound like antibiotic that can be considered a substance, produced by one microorganism, which in low concentration inhibits the growth of other microorganisms. Actinomycetes, slow-growing gram-positive bacteria, are the major sources of bioactive compounds. This study aimed to screen and identify antibacterial secondary metabolite-producing actinomycetes by sequencing the 16S rRNA method (molecular identification) from the soils of the mountain region of eastern Nepal. Starch casein agar (SCA) medium was used for the isolation of actinomycetes which were confirmed by primary screening and secondary screening. Identification of presumptive genera was done based on macroscopic, microscopic, and biochemical characteristics and confirmed by sequencing their 16S rRNA genes. The antibacterial compound was produced by culturing the potential isolate in starch casein broth. Using organic solvents such as ethyl acetate, n-butanol, chloroform, dichloromethane, and methanol, the chemical was recovered from the fermented broth. TLC performed the antibacterial substance characterization. Only 9 (13.6%) of the 66 actinomycetes isolates showed antibacterial activity against test microorganisms. Only one of the nine isolates, M3, had antibacterial activity in primary screening against gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli, Salmonella Typhi, Shigella spp., and Pseudomonas aeruginosa) test bacteria. M3 was chosen for secondary screening due to its strong antibacterial activity. The minimum inhibitory concentration (MIC) of crude antibacterial substances was found to be 2.5 mg/mL against test organisms. According to the TLC chromatogram, the isolate produced only one compound with an Rf value of 0.81, completely distinct from the spot formed by gentamicin (standard), which had an Rf value of 0.89. The isolates were considered Streptomyces spp., a distinct taxonomic group based on characterization by macroscopic, microscopic, biochemical, physiological, and molecular techniques. This study concluded that Mountain regions are the reservoir of antibiotic- producing actinomycetes. Streptomyces is the most common genus.

BACKGROUND:Ruta graveolens is one of the most used phytomedicines. To date, there is no report of determining the bioactivity of R. graveolens against cariogenic causing bacteria (Streptococcus mutans and Streptococcus sobrinus).OBJECTIVE:The objective of the present study was to determine the antibacterial activity and metabolite profile of R. graveolens against S. mutans and S. sobrinus.MATERIALS AND METHODS:R. graveolens plant material was collected and processed in the month of February. The plant material was extracted by Soxhlet apparatus using methanol solvent. Two strains of S. mutans and two strains of S. sobrinus were isolated from dental caries-active participants and cultured on mitis salivarius-bacitracin agar. The antibacterial susceptibility testing of methanolic extract of R. graveolens was performed by disc diffusion method. The metabolite profile of the plant extract was determined using electrospray ionization-tandem mass spectrometry.RESULTS:The methanolic extract of R. graveolens showed a promising antibacterial activity against S. mutans and S. sobrinus. Two compounds named γ-fagarine and kokusaginine were identified from the methanolic extract of R. graveolens.CONCLUSION:The study concluded that R. graveolens contains significant antibacterial activity. However, further investigations are suggested to understand the anticaries properties of these pure compounds.